Published Aug 21, 2023
Most potters don’t give much thought to kiln wash and just use the recipe they used when they first learned about firing kilns. Or they just grab whatever happens to be in the kiln wash bucket. But considering kiln wash more carefully might help potters avoid some of the common kiln wash headaches—like scraping cracked kiln wash off shelves, or lamenting an otherwise perfect piece that was ruined by a flake of kiln wash.
This post comes to us from ceramic artist Sylvia Nagy of Brooklyn, New York. If you are tired of scraping and cleaning kiln shelves between firings, you'll love this simple tip. — Jennifer Poellot Harnetty, editor
Worried about your kiln wash flaking?
Kiln wash is usually a mixture of alumina hydrate and kaolin. If kiln shelves with this typical mixture of kiln wash are not scraped and cleaned in between firings and the kiln shelves are flipped between firings to prevent warping, pieces of kiln wash can flake off, drop onto glazed ware and ruin the surface. Kiln wash should be used in both electric kilns and gas kilns.
I have found that using alumina hydrate mixed only with water eliminates the problem of flaking kiln wash and works just as well. I just brush the mixture on my kiln shelves and, after firing, it becomes powder again. Cleaning the shelves is as easy as brushing the powder from the shelf. You can even save the powder, remix it with water and use it again next firing. An added bonus is that the powder enables the ceramic pieces to move a bit during the firing, which cuts down on warping that my occur during shrinkage.